Radioactive Tracers and the Nobel Prize for Chemistry

Monday - October 9 2023, 17:28 UTC - 1 year ago

George de Hevesy's experiment of experimenting with food leftovers at a boarding house in Manchester, U.K., in 1911 led to the discovery of a powerful science tool, called radioactive tracers. Radioactive tracers are unstable isotopes which transform into a different element on radioactive decay, and their radioactivity serves as a signature indicating the presence of a given isotope. The successful use of this closely-monitored substance in a variety of sciences, including medicine and physics, led to George de Hevesy's Nobel Prize in Chemistry win in 1943.

Each October, the Nobel Prizes celebrate a handful of groundbreaking scientific achievements. And while many of the awarded discoveries revolutionize the field of science, some originate in unconventional places. For George de Hevesy, the 1943 Nobel Laureate in chemistry who discovered radioactive tracers, that place was a boarding house cafeteria in Manchester, U.K., in 1911.

De Hevesy had the sneaking suspicion that the staff of the boarding house cafeteria where he ate at every day was reusing leftovers from the dinner plates – each day’s soup seemed to contain all of the prior day’s ingredients. So he came up with a plan to test his theory.

At the time, de Hevesy was working with radioactive material. He sprinkled a small amount of radioactive material in his leftover meat. A few days later, he took an electroscope with him to the kitchen and measured the radioactivity in the prepared food.

His landlady, who was to blame for the recycled food, exclaimed "this is magic" when de Hevesy showed her his results, but really, it was just the first successful radioactive tracer experiment.

We are a team of chemists and physicists who work at the Facility for Rare Isotope Beams, located at Michigan State University. De Hevesy’s early research in the field has revolutionized the way that modern scientists like us use radioactive material, and it has led to a variety of scientific and medical advances.

The nuisance of lead .

A year before conducting his recycled ingredients experiment, Hungary-born de Hevesy had traveled to the U.K. to start work with nuclear scientist Ernest Rutherford, who’d won a Nobel Prize just two years prior.

Rutherford was at the time working with a radioactive substance called radium D, a valuable byproduct of radium because of its long half-life (22 years). However, Rutherford couldn’t use his radium D sample, as it had large amounts of lead mixed in.

When de Hevesy arrived, Rutherford asked him to separate the radium D from the nuisance lead. The nuisance lead was made up of a combination of stable isotopes of lead (Pb). Each isotope had the same number of protons (82 for lead), but a different number of neutrons.

De Hevesy worked on separating the radium D from the natural lead using chemical separation techniques for almost two years, with no success. The reason for his failure was that, unknown to anyone at the time, radium D was actually a different form of lead – namely the radioactive isotope, or radioisotope Pb-210.

Nevertheless, de Hevesy’s failure led to an even bigger discovery. The creative scientist figured out that if he could not separate radium D from natural lead, he could use it as a tracer of lead.

Radioactive isotopes, like Pb-210, are unstable isotopes, which means that over time they will transform into a different element. During this transformation, called radioactive decay, they typically release particles or light, which can be detected as radioactivity.

This radioactivity acts as a signature indicating the presence of the radioactive isotope. This critical property of radioisotopes allows them to be used as tracers.

Radium D as a tracer .

A tracer is a substance that is used to monitor the pathway of a chemical or physical phenomenon. In de Hevesy’s case, he wanted to trace the movement of lead in biological systems. De Hevesy found that radium D was released during the radioactive decay of the parent radioisotope Pb-210, making it a viable tracer for lead.

In the decades that followed, radioactive tracers became a valuable tool for scientists that wanted to study the movement of any kind of material in living organisms. This research revolutionized the fields of medicine and physics, and it earned de Hevesy the 1943 Nobel Prize in Chemistry for his pioneering work.

Nowadays, radioactive tracers are used in a wide range of chemical research. This includes radiopharmaceuticals, which are drugs made up of radioisotopes that can be used in medical imaging to detect certain types of cancer. At the Facility for Rare Isotope Beams, we use tracers to study rare isotopes that are difficult to detect any other way.

Thanks to de Hevesy’s recycled soup experiment, science now has a powerful tool which allows us to observe and monitor the effects of radioactivity on the molecular level. His creative approach to study science has enabled countless scientific and medical discoveries, and it stands as a testament that science is not limited to laboratories and classrooms – it can be found outside of the box.